Sensitizing photographic silverhalide emulsions



March 3, 1936. w. SCHNEIDER 2,032,506

SENSITIZING PHOTOGRAPHIC SILVER HALIDE EMULSIONS Filed Jan. 14, 1955 40.] IIIIIIIIIIIIIIIIIIIIIIVIIIIIIIIIIIIIIIIII 700 600 .500 M0 Wax-2 emmcoma EJ1515 6 cfszfi/ar MM? IIIIIIIIIIIIIIIIIIIIIIITIIIIIIIIIII'IIIIIIIII'I'IITIIIIIIIIIITIIIIIIIIIIIIIIIYIIIII In van for WM QM By Affo'rneyPatented Mar. 3, 1936 PATENT oFFicE snnsrrrzmc rno-rocasrnio .srnvanmumsnmsrons Wilhelm Schneider, Dess'au in Anlialt, Germany,

assignor to Agia Ansco Corporation, Binghamton, N. Y., a corporation ofNew York Application January 14, 1933, Serial No.851,846

InGe

many January 19, 1932 My present invention relates to sensitizing ofphotographic emulsions.

One of its objects is to provide such an emulsion the sensltiveness. ofwhich is raised over that to which the emulsion is normally sensitive.Further objects will be seen from the detailed speciflcation followinghereafter. Reference is made .to the accompanying drawing which shows,the

spectrogram of a silver bromide emulsion containing about 1.5 per centof silver iodide without the incorporation of a sensitizer andspectrograms of the same emulsion sensitized with my new sensitizers.

I have found that photographic silver halide emulsions are sensitized byincorporating in the emulsion a symmetrical or unsymmetrical dye-'-stuff corresponding with the following general formula wherein-x and Ystand for the bivalent atoms oxygen, sulphur or selenium r a salt ofsuch a dyestuff.

Most of the sensitizers hitherto known have basic character. In contrastthereto the dyestuffs of the above formula are acid dyestufis and aremetals. The formation of salts occurs by reaction of bases withtheZH-group which may be a- .OH-, 51-1, or SeH-group. Between the ZH-groupand the -W group there exists a corfiugate systent of double bonds whichproduces the color characteristics of these compounds.

The simplest dyestuffs in which the two heterocyclic nuclei are linkedtogether by one carbon atom are obtained by condensation of, for instance, coumaranone, 3 hydroxythionaphthene or 3-ludn'ixyselenonaphthene with chloroform or orthoformic acid ester andsodium ethylate.

The hydrogen linked to the bridging carbon atom can be replaced by alkylor halogen. Com= pounds of such kind, having the following formula areobtained by condensing, for instance, coumaranone, gtl-hydroxy-thionaphthene or 3-hydroxy-selenonapthene withtetra-halogen-methcapable of forming salts with, for instance, alkaliane, an ortho acetic acid triester, an orthopropionic acid triester andso on or with a ketono of the general formula (wherein X has the meaningabove defined and it. stands for l).

Fm'thermore' thehvdro'gen atoms of the ring systems. can be substituted.in 4.4'-, 5.5'-, 6.8-, -7.'7-position by, for instance, halogen, alkylor alkyloxy, sulphallryl, or an unsubstituted or substituted aminogroup.

Furthermore the benzene nucleus can be re- -.placed by condensed ringsystems, for instance, naphthalene, antne, acenaphthene, diphenyloxide,or carbazole. X and Ymay bethe'same or different bivalent "atoms of thegroup oxygen selenium and sulfur. When x and Y represent the sameelement there are obtained etrical dyestufls, whereas asymmetricaldyestuffs are obtained when X and Y are differentpetrical dyestuifs canbe obtained by condensing an aldehyde of the general formula for oxygen,sulphur or selenium, with .coranone, 3-hydroonaph=.thene,,3-hydromselenonaphthene, in acetic acid in the presence ofsodium ethylate or hydrogen chloride.

Furthermore, by choosing suitable components for the condensation,unsymmetricaldyestuffs may be prepared in which the unsymmetrical natureis 'due to substitution in one of the ring v products maybe made in themanner described 56 with No. 2 shows the spectrograms sensitized with.

No.3showsthespectrbgrsmoftheemulsion sensitized with I Lei-i No. 4 showsthe spectrogram the emulsion i .os.

'lhedvestuiismaybeaddedinfosmofasolutiontothoemulsioninanyamountandlnanystage of its manufacture. A suitable solvent is; for instance, alcohol.As a rule I have found 10 'tozflmilligramsofdyestuifperkilogramofemulsiontobeasuitable additmnbutmyinvention is not limited'lhedyestufismayfurthermorebeaddedto' the emulsion in form of theirsilver salts dissolved in an alcoholic solution of ammonia.

For sensitizing the plates according to tlm bathing methodtheyarejfcrinstance, treatedin an alcoholic aqueous solution of dyestufl with Itheadditionofasmallproportionofammonmv" The following examples serve toillustrate the inventionz- Example i.---The dye corresponding withfollowing formula I s s I is obtainable by dissolving 0 gram ofs-byaroxythionaphthene in i5 cc. of alcohol, adding 1.6

cc. of chloroform and heating the solution to boilinginarefluxapparatus.'iherearethen addedizgramsofsodiumethylaieinformofa Super centsolutioninalcoholwhereuponthe' mixtureassumesavioletcoior.Aftereo'olingthe dyeseparatesflsisfllteredandwashedwithws tor. It mayberecrystsllisedfromalcohol andvistlienobtainedinformofcryst'alsoiifametallic lusterandabluish-redcola.

Asilverbromideemulsionecntamingabout percentofsilveriodidesensitimdwithhem has'amaximumofsensitivenematawavelength ofaboutm I tsamplezwhenworkingaccordingtothe methoddescribedinlsampleibutstartingfrom 2molecular of s-brdrwselsnonaphthene, 1 molecular proportion ofchloroform and 8 'molecular proportions of sodium ethylate, a dyestuilis obtained corresponding with the following formula I c=o n noc------ sSo A silver bromideemulsion containing about 4 per cent of silver-iodidesensitized with the dye has a maximum of sensitiveness at a wave lengthof about 590 pp. 7

Example 3.The dye corresponding with the v following formula be producedby dissolving 3.0 grams ofthydronthionaphthene and 3.6 grams of -2-formvl- -3-hydroxv-thionaphthene in about 30 cc. of glacial acetic acidat ordinary temperature and then introducing hydrochloric acid into thesolution. The yellow compound which separates is suspended in a solutionof caustic alkali whereuponthe blue violet dye is formed. "lhe same maybe recrystallized from alcohol.

A silver bromide emulsion containing about 4 per cent of silver-iodidesensitized with the dye has a maximum of sensitiveness at a wave lengthof about 600 Example 4.-When working according to the method describedin Example 1 and starting from 1 molecular-proportion of3-hydroxyselenonaphthene, 1 molecular -proportion of 2-formyl-B-hydrow-4-methyl-6-chlorothionaphthene and 3 molecular proportions ofsodium ethylate; a dyestuf! is obtained corresponding with the followingformula I l CHs I A silver bromide emulsion containing about 4 per centof silver-iodide sensitized with the dye has a maximum of sensitivenessat a wave of about 595 i.- I Immple SF-When working according to themethod dgscribed in Examplel and starting from 2 molecular proportionsof S-hydronthionaphth'ene, 1 molecular proportion. ofcarbontetrachloride and 3 molecularproportions of sodium ethylate adyestuif is obtained corresponding with the following formula e-o 01 -0I a silver bromide emulsion containing about 4 per cent ofsilver-iodidesensitized with the dye has a maximumoi' sensitiveness at awave length of about 600 n. I

Hy invention is not limited to the foregoing "examples nor tothespeciiic details given therein. Numerous other embodiments arepossible and I. contemplate as included within my invention all suchmodifications and equivalents as fall within the scope of the appendedclaims.

Bo,forinstance,thebensenenucleimavcontain acaasos' other substituents.Theformulze of the dyes as given herein represent the molecularstructure of my new dyes so far as known. If, however, in

. future it should become evident that the formula wherein x and Y standfor the bivalent atoms sulfur or selenium. v

2. A photographic material comprising .a diver-halide emulsioncontaining a dye corresponding probably with the formula 3. Aphotographic material comprising a. silyer-halide emulsion containing adyecorresponding probably with the formula O ililijj Be 4. Aphotographic material comprising a suver-halide emulsion containing adye corre- I sponding probably with the formula methine dye.

5. A photographic material comprising a gelatino-silver-bl' mideemulsion about 4 per cent of silver iodide having incorporated the dyecorrespo nding probably with the ormula Y =0 HO-O having a ofsensitiveness at about 599 6. A photographic material comprising agelatino-silver-bromide emulsion containing about 4 per cent of silveriodide having incorporated the dye corresponding probably with theformula 1513;! a maximum of aensitiveness atabout 7'. A photographicmaterial tino-s'ilver-bromide emulsion containing about 4 per cent ofsilver iodide having incorporated the dye corresponding probably withthe formula having a maximum or sensitiveness .1, about 595 pp. v

a. A photographic mam-m comprising a silver comprising a s containinghalide emulsion containing a di-(3-hydronthionaphthene-2) -methine dye.

9. A photographic material comprising a silver halide emulsioncontaining a 'di- (3-hydroxyselenonaphthene-m -methine dye.

10. A photographic material comprising'a silyer halide emulsioncontaining a (S-hydroxythi naphthene 3 hydroxyselenonaphthene) 2 2WILHIL'II SCHNEIDER.

